Are wearable electronic vision enhancement systems (wEVES) beneficial for people with age-related macular degeneration? A scoping review.

INTRODUCTION: Age-related macular degeneration (AMD) is the most common cause of irreversible visual impairment in the United Kingdom. It has a wide-ranging detrimental impact on daily living, including impairment of functional ability and quality of life. Assistive technology designed to overcome this impairment includes wearable electronic vision enhancement systems (wEVES). This scoping review assesses the usefulness of these systems for people with AMD. METHODS: Four databases (Cumulative Index to Nursing and Allied Health Literature, PubMed, Web of Science and Cochrane CENTRAL) were searched to identify papers that investigated image enhancement with a head-mounted electronic device on a sample population that included people with AMD. RESULTS: Thirty-two papers were included: 18 studied the clinical and functional benefits of wEVES, 11 investigated use and usability and 3 discussed sickness and adverse effects. CONCLUSIONS: Wearable electronic vision enhancement systems provide hands-free magnification and image enhancement producing significant improvements in acuity, contrast sensitivity and aspects of laboratory-simulated daily activity. Adverse effects were infrequent, minor and spontaneously resolved with the removal of the device. However, when symptoms arose, they sometimes persisted with continued device usage. There are multi-factorial influences and a diversity of user opinions on promotors to successful device use. These factors are not exclusively driven by visual improvement and incorporate other issues including device weight, ease of use and inconspicuous design. There is insufficient evidence of any cost-benefit analysis for wEVES. However, it has been shown that a user's decision to make a purchase evolves over time, with their estimates of cost falling below the retail price of the devices. Additional research is needed to understand the specific and distinct benefits of wEVES for people with AMD. Further patient-centred research should assess the benefits of wEVES in user-led activities when directly compared with alternative coping strategies, allowing professionals and users to make better prescribing and purchasing decisions.

Can listening provide a useful clinical estimate of low vision reading parameters?

PURPOSE: The purpose of this study was to determine whether a clinician can assess critical print size (CPS) and/or reading fluency by listening to a visually impaired patient reading aloud across a range of print sizes on an MNREAD chart, rather than needing to plot and analyse reading speed data as a function of print size. METHODS: Fifty-six low vision participants were audio-recorded reading an MNREAD chart under standard conditions. Two experienced raters listened to the recordings and made judgments of the CPS (logMAR), and of the level of reading fluency achieved at large print sizes on a 4-point rating scale. Reading times were plotted as a function of print size to determine the CPS as the smallest print size that supported the participant's maximum reading speed (MRS) by inspection, and the MRS as the mean reading speed across print sizes including, and larger than, the CPS. RESULTS: Listened CPS judgments made for each rater were slightly larger than the CPS values obtained by inspection (mean differences 0.04logMAR (p = 0.06), 0.08logMAR (p < 0.01); limits of agreement (LoA) ±0.28logMAR, ±0.39logMAR, respectively). CPS judgments were consistent both between raters (mean difference 0.04logMAR [p = 0.18]; LoA ±0.42logMAR) and between two judgments made by each rater (mean differences 0.00logMAR (p = 1.0), 0.03logMAR (p < 0.05); LoA ±0.23logMAR, ±0.17logMAR). Reading fluency could be categorised as 'functional' (MRS > 80 wpm) or 'non-functional' (MRS < 80 wpm) with a sensitivity of 88%-90% and a specificity of 100%. CONCLUSIONS: Experienced raters listening to a patient reading an MNREAD chart can determine a clinically useful estimate of critical print size and can discriminate maximum reading speeds that are above and below that likely to provide sustained reading ability. Listening to a patient reading an MNREAD chart is an option for the low vision clinician's armoury of assessments.

Is patient identification of 'comfortable' print size a useful clinical parameter for low vision reading assessment?

PURPOSE: The purpose of this study was to determine what a person with vision loss considers a 'comfortable' print size to read, and examine whether this reflects any of three currently used parameters for identifying print size required for sustained reading tasks: minimum size to achieve maximum reading speed (the critical print size (CPS)); minimum size for functional reading at 80 wpm and/or a size that is double the reading acuity (representing an acuity reserve of 2:1). METHODS: Forty-seven participants entering low vision rehabilitation (mean age 77 years, 24 with macular degeneration) were assessed using MNREAD charts to determine reading acuity, maximum reading speed, CPS and the minimum size allowing functional (80 wpm) reading. Comfortable print size was assessed by asking participants to identify 'the smallest print size that you would find comfortable using' on the MNREAD chart. RESULTS: There was little difference between comfortable print size and CPS (mean difference 0.05 logMAR (SD 0.18); p = 0.08, limits of agreement ±0.35 logMAR), and no trend for the difference between values to differ across the functional range. Size for functional reading could only be assessed for 41 participants, and the difference between this and comfortable print size varied across the functional range. Comfortable print size was consistently smaller than twice the reading acuity size (mean difference 0.11 logMAR (SD 0.17); p < 0.001), with an average acuity reserve of 1.74:1. CONCLUSIONS: Asking people with visual impairment to identify a print size that is comfortable to read provides a print size similar to the CPS. This can be used as a guide in selecting magnification for sustained reading without having to undertake further analyses. Identification of perceived comfortable print size may offer a time-efficient clinical method of estimating magnification requirements, and be relevant for undertaking effective remote consultations.

Change in rehabilitation needs and activity limitations over time of adults with acquired visual impairment following entry to a low vision rehabilitation service in England.

PURPOSE: Longitudinal changes in priority rehabilitation needs, vision-related activity limitation and importance of visual goals were evaluated in a sample of people with a visual impairment over a year following entry to low vision rehabilitation services in England. METHODS: Participants were adults with newly registered visual impairment within Leicestershire. Priority scores, indicating the level of rehabilitative need, were determined from the importance and difficulty scores of the 48 goals of the Participation and Activity Inventory (PAI). Rasch analysis of the difficulty and importance scores examined activity limitation and importance separately. PAI outcome measures were assessed on entry to rehabilitation services and at 4 and 12 months thereafter. RESULTS: Forty-eight participants (mean age 74.2, SD 14.1 years) completed three visits. Overall, there was a statistically significant reduction in the perceived need for rehabilitation over time (p < 0.001, ηp2  = 0.29), driven by reduced perceived difficulty (p < 0.001, ηp2  = 0.32) but stable importance (p = 0.73) of goals, with most change occurring between baseline and 4 months. PAI goals with greatest rehabilitative need at study entry were reading, mobility and writing, and these remained of highest priority over time. The greatest priority score decrease was for the goal 'Hobbies and crafts'. The largest decrease in importance was for 'Mobility outdoors', whereas 'Relationship with loved ones' increased most. CONCLUSIONS: Despite a decline in the perceived need for rehabilitation over the study period, there remains a need for continued support and intervention at 12 months following registration with rehabilitation services, particularly for the key goals of reading, writing and mobility. Early identification and support for individuals' important but difficult goals could prevent such goals being relinquished. Goals concerning relationships and communication became more important over time, indicating that re-evaluation of needs at follow-up is necessary to inform ongoing service provision.

How Is Jump Performance Affected in Male Athletes when Completed with a Visual Impairment?

SIGNIFICANCE: High-, long-, and triple-jump athletic events may need to consider whether it is appropriate to group vision-impaired athletes in the same classification with loss of different visual functions, and a greater emphasis may need to be placed on the visual field (VF) within the current classification system used. PURPOSE: Athletes with vision impairment are grouped, based on their visual function, into one of three different classes (B1, B2, and B3, with B1 being the most severe). Athletes in class B2 have loss in visual acuity (VA; range, 1.50 to 2.60 logMAR) or VF (constricted to a diameter of <10°). The current study investigated how loss of different visual function (VA or VF) within the same class impacts jumping performance, a fundamental component in long-, triple-, and high-jump athletic events. METHODS: Ten subelite male athletes (age, 21.6 ± 0.96 years; height, 178.8 ± 2.97 cm; mass, 82.2 ± 10.58 kg) with normal vision who participate in athletics were recruited. Participants completed drop jumps in four vision conditions: habitual vision condition (Full), VA no better than 1.60 logMAR (B2-VA), VF restricted to <10° (B2-VF), and VA no better than 1.30 logMAR (B3-VA). RESULTS: Meaningful differences were observed between Full and B2-VF conditions. After rebound, vertical velocity at take-off was highest in Full condition (2.84 ± 0.35 m · s-1; 95% confidence interval [CI], 2.68 to 2.99 m · s-1) and was lowest in B2-VF condition (20% reduction; 2.32 ± 0.29 m · s-1; 95% CI, 2.16 to 2.48 m · s-1). Peak vertical jump height was highest in Full (0.42 ± 0.10 m; 95% CI, 0.38 to 0.46 m) and reduced by 40% in B2-VF (0.28 ± 0.07 m; 95% CI, 0.24 to 0.32 m). Minimal differences were found between Full and B2-VA, or B3-VA conditions. CONCLUSIONS: Jump performance is compromised in athletes with simulated vision impairment. However, decrements in performance seem specific to those with severely constricted VF. Those with reduced VA (in B2-VA and B3-VA classes) seem to produce performance comparable to those with normal vision.

Designing an internet-based intervention for improving wellbeing in people with acquired vision loss: A Delphi consensus study.

PURPOSE: Vision impairment (VI) may impact a person's functional ability resulting in a loss of independence, anxiety, depression, social isolation and reduced quality of life. Caregivers also experience similar problems due to the increased burden placed on them. Support to address these difficulties encountered by those with VI and their caregivers may not always be accessible. An internet-based intervention may provide more accessible support. The aim of this study was to obtain consensus regarding the content and accessibility features required to design an internet-based intervention to promote wellbeing for people with VI and their caregivers. METHOD: A three-round Delphi review was conducted with a panel of 30 stakeholders. Three stakeholder groups were included, namely individuals with vision loss, experts in the field of vision loss and mental health and carers of individuals with vision loss. Conceptual wellbeing ideas were examined in round 1, the intervention modules and module content were proposed in round 2 and refined in round 3. RESULTS: Consensus of 75% or more was reached to include 18 modules into the intervention. These were divided into seven sections: understanding vision loss, emotional wellbeing, functional wellbeing, social wellbeing, physical wellbeing, wellbeing for carers and maintaining wellbeing. The accessibility features deemed most important were font size, colour and contrast options, compatibility with low vision aids and layout of the intervention. CONCLUSIONS: The Delphi process positively informed the design of an internet-based intervention for individuals with acquired VI and their caregivers. Suggestions provided by stakeholders should now be incorporated into the intervention. Future evaluation of efficacy and cost-effectiveness of such an intervention are necessary.

Do visual fields need to be considered in classification criteria within visually impaired shooting?

Classification within the sport of vision impairment (VI) shooting is based upon the athlete's visual function. This study aimed to determine whether more than one class of competition is needed within VI shooting on the basis of visual field loss. Qualification scores of 23 elite athletes were obtained at World Championship events in prone and standing shooting disciplines. Visual field data were obtained from classification data and from assessment at events. A standardized scoring protocol determined whether athletes had function (≥10 dB) or no function (<10 dB) at locations between 0-60 degrees eccentricity along 10 meridia. Visual field function was not associated with shooting performance in prone or standing disciplines (p > 0.05). Having measurable visual field function beyond 30 degrees made no difference to athletes' ability to shoot competitively in prone (p = 0.65) or standing disciplines (p = 0.47), although a potential impact on qualification was observed in the standing discipline. There was no evidence that loss of visual field function at any specific location adversely affected ability to shoot competitively. There is currently no evidence to consider visual fields in classification within prone or standing VI shooting, although further research is needed as the sport grows.

Rehabilitation needs and activity limitations of adults with a visual impairment entering a low vision rehabilitation service in England.

PURPOSE: To evaluate outcome measures of the Participation and Activity Inventory (PAI) in a sample of adults with acquired visual impairment entering vision rehabilitation. Both Priority Scores, indicating level of rehabilitative need, and Person Measures, indicating goal difficulty, were considered. METHODS: Participants were newly registered adults with visual impairment within Leicestershire, United Kingdom. The importance and difficulty of 48 goals of the PAI were assessed, as were demographic factors, clinical visual function (visual acuity, contrast sensitivity, reading function) and psychosocial function (adjustment to visual loss, depression, anxiety and fear of falling). Priority scores were calculated as the product of importance and difficulty of each goal. All questionnaires were Rasch analysed, and person and item measures of perceived difficulty with goals were derived. RESULTS: Sixty people (mean age ± S.D. = 75.8 ± 13.8 years) took part. PAI goals with greatest rehabilitative need were reading (6.82 ± 2.91), mobility outdoors (6.55 ± 3.92), mobility indoors within an unfamiliar environment (5.52 ± 3.93) and writing (5.27 ± 3.02). Greater rehabilitative need was associated with younger age (ß = -0.46, p < 0.001), and with higher depressive symptomatology (ß = 0.35, p < 0.01; model R2 34%). Goals with greatest difficulty were mending clothing (-1.95 ± 0.35 logits) and hobbies and crafts (-1.32 ± 0.23 logits). Greater difficulty was associated with higher depressive symptomatology (ß = 0.39, p < 0.001), lower visual acuity (ß = 0.42, p < 0.001) and lower adjustment of visual loss (ß = 0.31, p < 0.01; model R2 53%). CONCLUSIONS: Key rehabilitation needs for adults at entry to services require both optical and non-optical interventions. As rehabilitative need was not associated with the level of visual impairment, eyecare professionals should not wait until the end of medical treatment before referral for support. Similarly, rehabilitative need was associated with younger age, indicating the importance to refer younger people with sight loss at an early stage. The use of structured assessment, such as the PAI, ensures goals that have an impact upon quality of life are specifically identified. Depression screening on entry to rehabilitation is relevant as it predicts both perceived difficulty and rehabilitative need.

Relative Difficulties of Daily Living Tasks with Retinitis Pigmentosa.

PURPOSE: To determine the relative difficulty of activity of daily living tasks for people with retinitis pigmentosa (RP). METHODS: Participants with RP (n = 166) rated the difficulty of tasks (n = 43) underpinning the Dutch Activity Inventory goals of mobility indoors and outdoors, shopping, and using public transport. Demographic characteristics were also determined. Responses were Rasch analyzed to determine properties of the scale, derive unidimensional subscales, and consider differential item functioning (DIF). RESULTS: After removal of one ill-fitting item, the remaining 42 tasks formed a scale with reasonable Rasch parameters but poor unidimensionality. The most difficult tasks were orienting in poor and bright light both indoors and outdoors, and avoiding peripheral obstacles outdoors. Eight subscales were derived with unidimensional properties, each of which could be considered as requiring similar skills. DIF identified that tasks from the "poor light and obstacles" subscale were more difficult for those younger than the median age, nonusers of mobility aids, and those not registered or registered sight impaired. Tasks from the "finding products" and "public transport" subscales were more difficult for those older than the median age, with longer duration of visual loss, users of mobility aids, and those registered severely sight impaired. CONCLUSIONS: The most difficult tasks for people with RP of orienting in poor light and avoiding peripheral obstacles are relatively more difficult for those not registered as "severely sight impaired," but are less difficult for those who use mobility aids. Mobility aids (guide dog or cane), therefore, do benefit users in their perceived ability in these particular tasks. The derived unidimensional subscales reorganize the tasks from those grouped together by goal (researcher driven) to those perceived as requiring similar skills by people with RP (patient driven) and can be used as an evidence base for orientation and mobility training protocols.

Functional visual fields: relationship of visual field areas to self-reported function.

PURPOSE: The aim of this study is to relate areas of the visual field to functional difficulties to inform the development of a binocular visual field assessment that can reflect the functional consequences of visual field loss. METHODS: Fifty-two participants with peripheral visual field loss undertook binocular assessment of visual fields using the 30-2 and 60-4 SITA Fast programs on the Humphrey Field Analyser, and mean thresholds were derived. Binocular visual acuity, contrast sensitivity and near reading performance were also determined. Self-reported overall and mobility function were assessed using the Dutch ICF Activity Inventory. RESULTS: Greater visual field loss (0-60°) was associated with worse self-reported function both overall (R2 = 0.50; p < 0.0001), and for mobility (R2 = 0.64; p < 0.0001). Central (0-30°) and peripheral (30-60°) visual field areas were similarly related to mobility function (R2 = 0.61, p < 0.0001 and R2 = 0.63, p < 0.0001 respectively), although the peripheral (30-60°) visual field was the best predictor of mobility self-reported function in multiple regression analyses. Superior and inferior visual field areas related similarly to mobility function (R2 = 0.56, p < 0.0001 and R2 = 0.67, p < 0.0001 respectively). The inferior field was found to be the best predictor of mobility function in multiple regression analysis. CONCLUSION: Mean threshold of the binocular visual field to 60° eccentricity is a good predictor of self-reported function overall, and particularly of mobility function. Both the central (0-30°) and peripheral (30-60°) mean threshold are good predictors of self-reported function, but the peripheral (30-0°) field is a slightly better predictor of mobility function, and should not be ignored when considering functional consequences of field loss. The inferior visual field is a slightly stronger predictor of perceived overall and mobility function than the superior field.

What choices of visual correction do people make for recreational running?

PURPOSE: Recreational runners who need refractive visual correction will need to choose the type of visual correction (spectacles, contact lenses, or no correction) to wear when running. The prevalence of correction choices and distinguishing demographic features associated with these choices of correction were investigated. METHODS: A 26-item online questionnaire covering demographics, running habits, and visual corrections used was answered by 941 people. Participants were aged 18 years or older, considered themselves a recreational runner and reported needing refractive correction for everyday life. Bivariate analyses and binary logistic regression were used to determine the variables independently associated with including or avoiding types of correction for running. RESULTS & CONCLUSIONS: Participants ran an average of 3.8times, 3.6hours, and 33.4km per week. Running habits were not associated with type of visual correction, suggesting that visual correction does not present a barrier to participating in recreational running. Solely using spectacles for running was the most common choice (38.8%) and they were worn for running at least sometimes by 65.8%. Fewer people wore spectacles for running than for general purposes (98.9%), suggesting spectacles have limitations for running. Spectacle wear for running was significantly associated with not having contact lenses available and longer duration of wearing visual correction. Running without correction was a common choice, with 15.5% of the sample only running without correction, and 26.2% running at least sometimes without their visual correction. Not wearing correction was significantly associated with not having contact lenses, a shorter duration of wearing visual correction, and a lower myopic refractive error. Contact lenses were the sole correction for running for 15.6% and were worn for running at least sometimes by 40.5%. Contact lenses were significantly more likely to be used by women and younger runners. Signposting runners to contact lenses if this has not previously been considered is recommended.

Evaluation of an emotional support service for the visually impaired.

PURPOSE: To evaluate the impact of a facilitated peer group emotional support service on visual quality of life (VQoL). METHODS: Consecutive participants in an emotional support service delivered to groups of up to six and facilitated by trained counselors were recruited (n = 29). The VCM1 (Vision Quality-of-life Core Measure) instrument was administered to participants at the start of the service, at the end of the service, and 6 months after completion of the service. RESULTS: For the group as a whole, VQoL significantly improved between the beginning of the service and the end (F(1,23) = 16.43, p = 0.000) but was no better than at the start 6 months later (F(1,23) = 3.60, p = 0.07). However, those with poorer initial VQoL showed significantly greater improvements after 6 months (1.74 ± 2.21 logits) than those with higher initial VQoL (-0.12 ± 0.71 logits) (t23 = 2.89, p = 0.008). The effect size of the intervention for those with poor initial VQoL was 1.10 at the end of service and 0.92 after 6 months. The items that became and remained easier were "feeling lonely or isolated due to eyesight," "feeling sad or low due to eyesight," and "feeling worried about general safety outside the home." CONCLUSIONS: This facilitated peer group emotional support service significantly improves VQoL as assessed with the VCM1 over at least 6 months for those with poorer initial VQoL. Different interventions may be needed for those with initially good VQoL and to improve other aspects of QoL not influenced by the service.

A randomised clinical trial to assess the effect of a dual treatment on myopia progression: the Cambridge Anti-Myopia Study.

PURPOSE: To evaluate the effect of a dual treatment modality for myopia, by improving accommodative functions, on myopia progression. METHODS: A double blind randomised control trial was conducted on 96 subjects. The treatment modality for the trial employed custom designed contact lenses which control spherical aberration in an attempt to optimise static accommodation responses during near-work, and a vision-training programme to improve accommodation dynamics. Myopia progression was assessed over a 2 year period using cycloplegic autorefraction and biometry. RESULTS: The mean progression was found to be -0.33 Dioptres (D) over the 2 years of the study. There was no interaction between contact lens treatment and vision training treatment at 24 months (p = 0.72). There was no significant treatment effect of either Vision Training or Contact Lens Spherical Aberration control on myopia progression. CONCLUSIONS: This study is unable to demonstrate that the progression of myopia can be reduced over a 2 year period by either of the two treatments aimed at improving accommodative function. Neither treatment group (contact lens or vision training) progressed at a slower rate over the 2 years of the study than did the appropriate control group.

Further Validation of Comfortable Print Size as a Parameter for Clinical Low-Vision Assessment.

Purpose: Comfortable print size (CfPS) has been proposed as a clinical alternative to deriving critical print size (CPS) in the assessment of reading function of vision-impaired patients. This study aimed to assess the repeatability of CfPS and to compare assessment duration and values to CPS measures and acuity reserves. Methods: Thirty-four adults with vision impairment had their reading function assessed. Two assessments of CfPS were made by asking, "What is the smallest print size that you would find comfortable using?" Reading parameters including CPS were determined using the MNREAD card chart and MNREAD app. Results: CfPS was quicker to assess (mean ± SD, 144 ± 77 seconds) than the MNREAD card (231 ± 177 seconds) or app (285 ± 43 seconds). Within-session repeatability of CfPS showed no significant bias or variation across the functional range and limits of agreement (LoA) of ±0.09 logMAR. CfPS values were 0.10 logMAR larger than card CPS values, but no different from app CPS values, with LoA of ±0.43 to 0.45 logMAR. Acuity reserve (comparing CfPS to card reading acuity) was 1.9:1 on average, with a maximum of 5.0:1. Conclusions: CfPS offers a quick, repeatable, and individualized clinical measure of the print size required for sustained reading that reflects CPS values obtained by more traditional measures. Translational Relevance: CfPS is an appropriate clinical measure of reading function to use in determining the magnification requirements of vision impaired patients for sustained reading tasks.

"I'm like something out of star wars": a qualitative investigation of the views of people with age-related macular degeneration regarding wearable electronic vision enhancement systems.

PURPOSE: This study explores the initial views of people with age-related macular degeneration towards wearable electronic vision enhancement systems. METHODS: Ten adults with age-related macular degeneration participated in semi-structured interviews, which were analysed using reflexive thematic analysis. RESULTS: Four themes were identified. Firstly, participants spoke of the wide-ranging impact of sight loss and how current helpful coping strategies still had significant limitations, affecting their desire to seek new solutions. The second theme showed that "other people" offered welcomed support with existing electronic coping solutions and are needed to provide suitable advice and training. However, "other people" limited the acceptability of using new solutions in public places. The third theme captured participants' desire for a wearable aid providing image magnification and enhancement over a range of distances. The final theme covered the reality of some current wearable technology, perceived as heavy, enclosing, or strange in appearance. Appearance caused some to lose interest in use, although others reframed the devices' desired usefulness to solo and sedentary activities. CONCLUSION: This population are interested in the potential benefits of wearable electronic vision enhancement systems. More work is needed to understand the suitability of current solutions due to participant concerns about training, appearance and performance.

A device that offers image enhancement and variable magnification in a hands-free, wearable form is very desirable to people with age-related macular degeneration.Some potential users are not seeking new solutions to well-described problems, which may be a useful coping strategy but alternatively may be motivated by fear of the unknown, financial worries, or concerns about appropriate training.The weight and appearance of some of the current wearable electronic vision enhancement systems are not immediately appealing and would stop some from proceeding with a performance trial.After viewing the current devices, the desirable times to use a wearable electronic vision enhancement system may be reframed by users to focus predominately on sedentary tasks taking place in isolation at home.

Guidelines for predicting performance with low vision AIDS.

PURPOSE: To determine predictors of success in reading with low vision aids, in terms of reading acuity, optimum acuity reserve, and maximum reading speed, for observers with vision loss from various causes. METHODS: One hundred people with vision loss affecting their daily lives participated. Clinical visual function measurements of distance acuity, contrast sensitivity, binocular threshold visual fields, and near reading performance with a MNRead chart at 40 cm were obtained. Reading performance aided by habitual low vision aids was also assessed with a MNRead chart. RESULTS: Aided reading acuity was best predicted by clinical reading acuity and contrast sensitivity. For most observers, a 2:1 acuity reserve was sufficient to achieve near-maximum reading speed, but one-third of observers with aided reading acuity better than 1.2 M required a higher acuity reserve. Aided maximum reading speed was best predicted by clinically assessed reading speed and by clinical reading acuity. CONCLUSIONS: People with vision impairment are likely to achieve 1 M with a low vision aid if their clinically assessed reading acuity is better than 0.85 logMAR. If acuity is worse than this, but contrast sensitivity is better than 1.05 logCS, 1M is also likely to be achieved. A 2:1 acuity reserve is adequate for 75% of observers, but those with good aided reading acuity may require further magnification to achieve best reading speeds. Fluent reading (>80 words per minute) is likely to be achieved if an observer reads fluently with large print at a fixed working distance and if clinically assessed reading acuity is better than 1.0 logMAR.

Important areas of the central binocular visual field for daily functioning in the visually impaired.

PURPOSE: To determine the areas of the central binocular visual field which correspond best with self-reported vision related activity limitations (VRAL) in individuals with visual impairment using a clinically relevant and accessible technique. METHODS: One hundred participants with mixed visual impairment undertook binocular threshold visual field testing using a Humphrey 30-2 SITA Fast program. The Activity Inventory (AI) was administered to assess overall, mobility related and reading related self-reported VRAL as part of a face-to-face clinical interview. Different eccentricities of the binocular field (central 5, 5-10, and 10-30°) were compared to self-reported VRAL in bivariate analyses and further explored using multivariate analyses. RESULTS: All areas of the binocular visual field were significantly associated with self-reported VRAL in bivariate analyses, with greater field loss associated with increased VRAL (p < 0.001). Multivariate analyses identified that function of the central 5-10° best predicted overall self-reported VRAL, and function of the central 5° (especially the right-hand-side) and the central 10-30° (especially 10-20°) best predicted self-reported VRAL in reading and mobility tasks, respectively. CONCLUSIONS: The results highlight the association between central binocular visual fields and self-reported VRAL in people with visual impairment. Central binocular fields can be measured using a widely available threshold test in order to understand the likely functional limitations of those with vision loss, particularly in mobility tasks. Self-reported VRAL can be estimated using the regression equations and graphs provided and difficulty levels in specific tasks can be determined.

Do best practice guidelines improve the legibility of pharmacy labels for the visually impaired?

PURPOSE: Reading pharmacy labels on medications is a challenging task for visually impaired people. Design for Patient Safety (DfPS) best practice guidelines exist on the presentation of information on pharmacy labels, but it is unclear to what extent current labels follow the guidance. It is also unclear whether labels produced to DfPS guidelines are more accessible to patients with impaired vision. METHODS: Twenty-four sample labels were obtained from six different pharmacy chains. Experimental labels were constructed reflecting a typical pharmacy label, an ideal label constructed to DfPS guidelines, and a large print label. 20 normally-sighted subjects read labels under habitual conditions (mean VA -0.14 log MAR, Snellen equivalent 6/4.4), and under two conditions of simulated visual impairment (mean VA +0.41 and +0.69 logMAR, Snellen equivalents 6/15.4 and 6/29.4). Outcome measures were speed and accuracy of label reading. RESULTS: Median font size for the primary directions on the sample labels was 9.5 point (range 8-10 point), rather than the recommended minimum size of 12 point. In the mild visual impairment condition, using the ideal label improved accurate reading speed by 58% over the typical label, and using the large print label improved accurate reading speed by about 100%. In the moderate visual impairment condition, 65% of subjects were able to see sufficient of the directions to be able to take the medication appropriately with the ideal label, and 80% with the large print label, as compared to 20% with the typical label. CONCLUSIONS: DfPS best practice guidelines were not fully met by any of the pharmacy labels in this sample. With unimpaired vision, label design had little impact on legibility. However, the results provide evidence that preparing pharmacy labels according to DfPS guidelines improves their relative legibility in simulated visual impairment. These findings need extending to those with actual visual impairment, but the current results strengthen the argument for conformance to DfPS guidelines.

Derivation of the acceptance and self-worth adjustment scale.

PURPOSE: The original 55-item Nottingham Adjustment Scale (NAS) is a first generation self-report instrument constructed using classical test theory to evaluate adjustment to vision loss. This study assesses the function of the NAS using Rasch analysis in a sample of adults with visual impairment and presents a revised second-generation instrument. METHODS: Ninety-nine subjects with established vision loss (median onset 5 years) were administered the NAS. Rasch analysis was performed to: (1) determine optimum response scale function, (2) aid item reduction, (3) determine reliability indices and item targeting, (4) assess unidimensionality using Rasch-based principal component analysis, (5) assess differential item functioning (notable defined as >1.0 logit), and (6) formulate person measures to correlate with Geriatric Depression Scale scores and distance visual acuity to indicate convergent and discriminant validity, respectively. RESULTS: Response categories exhibited underutilization, which when repaired improved response scale functioning and ordered structural calibrations. Misfitting items were removed iteratively until all items had mean-square infit and outfit values of 0.70 to 1.30. However, principal component analysis confirmed insufficient unidimensionality (two contrasts identified, eigenvalues 2.4 and 2.3). Removal of these contrasts and two further iterations restored unidimensionality. Despite item mistargeting (1.58 logits), the revised 19-item instrument demonstrated good person (0.85) and item (0.96) reliability coefficients, good convergent and discriminant validity, and no systematic differential item functioning. The resultant 19-item instrument was termed the Acceptance and Self-Worth Adjustment Scale (AS-WAS). CONCLUSIONS: In those with established vision loss, the 19-item Acceptance and Self-Worth Adjustment Scale is a reliable and valid instrument that estimates the level of adjustment concerned with acceptance, attitudes, self-esteem, self-efficacy, and locus of control. An additional measure of depression and anxiety is recommended to assess adjustment in a broader sense. Confirmation of item ordering is required if to be used in those with newly acquired vision loss.

Assessing visual activities of daily living in the visually impaired.

PURPOSE: Visual function assessment questionnaires ask people to rate the difficulty they have performing visual activities of daily living (ADLs). This study examines the relationship between self-reported difficulty and actual performance in such ADLs. METHODS: Twenty four subjects with established bilateral visual impairment initially self-reported their difficulty with 4 ADLs (reading newsprint, reading medicine labels, identifying coins and entering a PIN). Subjects' performance in variants of these ADLs was then assessed by measuring the time taken; by an observer rating subjects' performance; and by the subject rating their perceived difficulty with each specific task. Clinical visual function parameters were also assessed. RESULTS: Varying the assessed ADL task changed how well the task correlated with self-reported difficulty. Clinical visual function, rate of task completion and observer rating of difficulty all correlated significantly with self-reported difficulty, explaining up to 69% of the variance in self-reported difficulty. However, despite replicating the ADLs as closely as possible in the clinical environment the perceived difficulty of the clinic tasks was rated as being less than the initial self-reported difficulty of the real-world task. CONCLUSIONS: The task variant used is important when assessing functional visual performance directly. Timed and observer-rated methods of assessment can be appropriate for assessing functional vision. In this small study, the disconnect between self-reported visual difficulty and perceived or assessed difficulty suggests that functional performance is not the only factor influencing self-report, and responses to visual function assessment questionnaires should be interpreted in this light.